Chlorophyll pigment concentrations in water bodies; Dissolved oxygen parameters in the water column; Optical backscatter; Salinity of the water column; Temperature of the water column; Concentration of suspended particulate material in the water column; Alkalinity, acidity and pH of the water column

Investigations were carried out at approximately monthly intervals, but were occasionally repeated on consecutive days. Twenty-four days of field investigations were completed between July 1976 and March 1978, during which more than 70 profiles of chemical characteristics were recorded. A traverse of the entire estuarine mixing region took approximately 3 hours although at times shorter segments were investigated. All investigations in the field were carried out using a 12m length flat bottomed Rotork Seatruck. Water was pumped from a depth of 0.5m using a submersible (Flygt B2040) centrifugal pump through a constant levelled reservoir which held the detecting sensors. The following environmental data were recorded continuously during the traverses: temperature, salinity, chloride ion, pH, dissolved oxygen, turbidity and chlorophyll fluorescence.